Device for metering ignition fuel to the ignition unit of an afterburner associated with a turbojet engine

ABSTRACT

An installation for metering the ignition fuel to an ignition unit of an afterburner forming part of a jet engine, which utilizes a control device for regulating the injection period and/or the quantity of the ignition fuel as a function of engine parameters which vary with varying ambient conditions.

[4 1 Sept. 25, 1973 1 DEVICE FOR METERING IGNITION FUEL TO THE IGNITION UNIT OF AN [56] References Cited UNITED STATES PATENTS AFTERBURNER ASSOCIATED WITH A TURBOJET ENGINE Eberhard Bader, Munich,

10/1971 Tissier..............

[75] Inventor:

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[22] Filed: A r, 6, 1971 Attorney-Craig, Antonelli & Hill 57 ABSTRACT An installation for metering the ignition fuel to an igni- [21] Appl. No.: 131,713

Foreign Application Priority Data tion unit of an afterburner forming part of a jet engine, which utilizes a control device for regulating the injec- Apr. 9, 1970 Germany...................

tion period and/or the quantity of the ignition fuel as a function of engine parameters which vary with varying ambient conditions.

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INVENTOR EBERHARD BADER ATTORNEYS DEVICE FOR METERING IGNITION FUEL TO THE IGNITION UNIT OF AN AFTERBURNER ASSOCIATED WITH A TURBOJET ENGINE This invention relates to a device for metering the ignition fuel to the ignition unit of an afterburner associated with a turbojet engine with a first cylinder chamber for charging and discharging as well as for storing of the ignition fuel, for which purpose a control spool or piston axially movable against the force of a return spring is arranged in this first cylinder chamber, and with a second cylinder chamber adjacent to the first cylinder chamber and including a second control spool or piston, which is actuated by an external source and axially movable against the force of a return spring. This second control spool either releases the H.P. (high-pressure) fuel supply initiating the discharge motion of the first control spool by simultaneously shutting off the LP. (low-pressure) fuel supply or cuts off the H.P. fuel supply for the recharging motion of the first control spool with a simultaneous opening of the LP. fuel supply.

It is a known practice in jet engine to arrange an afterburner downstream of the compressor turbine of jet engines. In the case of an increased power requirement, the afterburner heats the turbine exhaust gases, thus producing an additional thrust. The ignition of the afterburner can be effected by an instantaneous ignition flame provided for a short period of time from the combustion chamber of the engine. For this purpose, additional fuel is supplied to the flame zone of the combustion chamber by way of a special injection nozzle causing the flame to expand through the turbine into the afterburner and thus effecting the ignition thereof. After afterburner lighting, or with the afterburner not operating, the additional fuel supply to the combustion chamber is interrupted or no additional fuel is supplied, respectively. g

A' device for metering the ignition fuel, which essentially-features thecharacteristics of the device as described hereinabove, is known from the German Patent 1,284,158.

This known device is to ensure a rapid charging and discharging of the ignition fuel as well as several consecutive ignition cycles recurring in short intervals with an exactly metered ignition fuel quantity and to assure great functional reliability due to its simple design.

Starting with this known solution, the invention is to solve the following problem:

Due to the operational mode of aircrafts equipped with turbojet engines and afterburners in low or high altitudes, these aircrafts are subjected to the varying atmospheric pressure, i.e., compared to the operation at low altitude the H.P. fuel pressure, for example, actuating a known device as mentioned above will considerably drop together with other engine parameters, such as the compressor inlet, the discharge pressure, etc.

Since in the case of this known device, the pressure of the fed H.P. fuel supply is the controlling parameter for the discharge time of the first control spool forcing the ignition fuel out of the device, when operating at high altitude the discharge time for the ignition fuel must be expected to be considerably longer than under operation at low altitude.

An injection time for the ignition fuel of excessive duration, however, results in an ignition flame which is the engine, which should be repeatable, if necessary, in

short-time intervals.

Starting with the device for metering the ignition fuel of the type described above, the present invention primarily proposes, as a solution to the above-described problem that means be provided which control the injection time and/or the ignition fuel quantity as a function of the varying operating parameters of a turbojet engine under various ambient conditions.

As a further embodiment of the inventive concept, such means could be constituted by pressure relief valves adjusted to suit the varying H.P. fuel pressures.

These valves could be arranged inside of the wall of the first cylinder chamber; however," they could also be arranged outside the first cylinder chamber, e.g., in pipes through which the excess fuel is returned to the fuel tank.

These valves could thus all be closed simultaneously if, for example, a specified minimum pressure of the H.P. fuel is not maintained, i.e., exceeded during the operation of the aircraft at low altitudes in order to prevent in this manner too rapid a discharge and an injection by the first control spool. Similarly, at aircraft operation at a certain higher altitude, all valves could be in the open position if a minimum pressure of the H.P. fuel is established during discharge motion of the first control spool, which is smaller than the spring pretension of the pressure relief valves. These valves can be so arranged and designed that they ensure essentially the same rapid light-off or ignition of the afterburner under any operating condition as a function of the pressure of the H.P. fuel increasing or decreasing with higher or lower flight altitudes in a linear manner.

Dependent upon the number of such valves with relatively small differences in pressure compensation, the aforementioned conditions could taken into specia consideration.

In a further embodiment of the present invention, an actuating spool or piston which is axially movable in a cylinder can be provided which, on one end, is loaded by a spring arranged in this cylinder, while the other end extending into the first cylindrical chamber of the device is subjected to the discharge fuel pressure; this other end is equipped with a contact pin pointing towards the inner surface of the first control spool which, upon contacting the first control spool, releases an electrical shut-off signal to the second control spool constructed as a solenoid valve.

Thisactuating spool limits the injection time and the ignition fuel quantity as a function of the pressure differential between the pre-loaded spring and the injection fuel.

According to the invention, the spring force acting on one end of the actuating spool may also be substituted by a pressure load, which is a function of varying engine parameters.

In lieu of the spring load acting upon one end of the actuating spool, this end could also be subjected to e.g. the compressor discharge pressure of the engine. It is also possible to apply a hydraulic pressure to the actuating spool, i.e., by means of a fluid, the pressure of which is dependent on the altitude and, more particularly, as a function of one or several engine parameters.

In a further embodiment of the present invention a rod of the first control spool, due to its discharge motion, may enter a cylindrical guide means which is surrounded by a current coil, the voltage of which is determined by an altitude-controlled dropping resistor. The inductive voltage, which can be tapped off at the current coil by the rod when entering the area of the cylindrical guide means surrounded by the current coil, serves to control the solenoid valve.

These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in conjunction with the accompanying drawing which shows, for purposes of illustration only, several embodiments in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal cross-sectional view of a device for metering the ignition fuel, according to the invention, with a schematic cut-away side view of a turbojet engine, including a fuel supply system of the engine and its associated afterburner.

FIG. 2 is a longitudinal cross-sectional view of a device for metering the ignition fuel, according to the invention, in a second embodiment and FIG. 3 is a longitudinal cross-sectional view of a third embodiment of a device for metering the ignition fuel according to the invention.

Referring now to the drawing wherein like reference numerals are used throughout the various views to designate like parts and, more particularly, to FIG. 1, the device according to the invention illustrated in the figure essentially comprises a cylindrical housing 1 with the first cylindrical chamber 2 in which a first control spool or piston 3 is axially movable against the action of a return spring 4. Adjacent to the cylindrical chamber 2, a second cylindrical chamber 5 is arranged in the cylindrical housing 1 with an axially movable second control spool or piston 6. The second control spool or piston 6 is loaded by a compression spring 7. The piston 6 includes a portion 61 cooperating with a coil 60 to form a solenoid valve. At the left-hand side of this device a cover 8 closes off and seals the first cylindrical chamber 2. A refilling valve 9 is arranged on top of this housing cover 8. Below the longitudinal center line 10 of the device, a cylinder 11 is mounted at the outside of the cover 8 with an axially movable actuating spool or shifting piston 12 located in this cylinder, which extends with a sleeve 13 thereof through a bore 14 arranged in the cover into first cylindrical chamber. The actuating spool or piston 12 extends on the right side towards inner surface 16 of the first control spool or piston 3 with a contact pin 15 bent upwards at its end and attached to the sleeve 13. The left-hand end of the actuating spool or piston 12 is loaded by spring 17 arranged in the cylinder 11; the pressure of the discharge fuel in the cylindrical chamber 2 acts upon the actuating spool or piston 12 by way of the right-hand end face 12' of the sleeve 13.

The turbojet engine 18, schematically shown above this device, essentially consists of a compressor 19, of a combustion section with combustion chambers 20, 21, of which several could be arranged coaxially to the engine longitudinal axis 22, and of a turbine 23 arranged downstream of and adjoining the combustion section. An afterburner jet pipe 24 with a variable thrust or final nozzle 25 at its end is arranged downstream of the turbine 23.

At first, reference should be made to a fuel supply system illustrated in simplified form for fuel injectors 26 arranged within the afterburner pipe 24 with flame holders 26' arranged downstream of the injectors, as well as for fuel injectors 27 arranged in the combustion chambers 20, 21. Two fuel pumps 31,32 are connected to a fuel tank 28 for supplying ignition fuel by way of lines 29, 30. Pump 31 serves for the supply with PM. fuel of the device according to the invention, while pump 32 serves for the supply with LP. fuel of the device. For the desired engine afterburner operation, it must be ensured that, as shown, the fuel injectors 26 can be supplied with fuel from tank 28 by way of the line 33 and the pump 34. This fuel pump 34 can be operated to start the fuel supply, for example, by means of a lever 35 and a linkage 36, shown schematically only by a full line.

In addition, it is also a prerequisite that with the engine operating, the fuel injectors 27 associated with the combustion chambers 20, 21 are supplied with fuel from the tank 28 by way of a fuel line 37 and the fuel pump 38. In order to be able to effect afterburner lightoff or ignition, the fuel pumps 31, 32 must be actuated by means of another lever 39 by way of linkages 40, 41 schematically shown in full lines, in order to supply fuel to the device according to the present invention.

In order to be able to act upon the device for metering the ignition fuel according to FIG. 1 with HP fuel, a fuel line 42 is connected to the fuel pump 31, which is connected by way ofa bore 43 with the second cylinder chamber 5. In the illustrated position, this bore 43 is sealed off by a front spool end piece 44, while the motion of the second control spool 6 caused by the force of the compression spring 7 is fixed by stop ring 45. For connecting the device also to the LP. fuel supply system, a line 46 is branched-off at the pump 32. Lines 47 and 48 are connected to line 46, with line 47 leading to the refilling valve 9 and line 48 to a bore 49 in the cylindrical housing 1. In the illustrated end position of the second control spool or piston 6, the bore 49 opens into the annular groove 50 of this control spool. One or several bores 51 pass through this second control spool or piston 6 within the area of this annular groove 50 and discharge into a bore 52 extending through this second control spool 6 in a longitudinal direction.

If the device is to be discharged now for afterburner ignition, the solenoid valve is actuated and then the first control spool or piston 3 is actuated against the force of the return spring 4 by the HP. fuel supplied by way of bore 43, cylinder chamber 5 and stop ring 45, and the fuel present in first cylindrical chamber 2 of the device can flow to the ignition fuel injectors 57, S8 arranged in the combustion chambers 20, 21 by way of bore 53, arranged in the housing cover 8, a line 54 connected thereto and by way of the lines 55, 56. The contact pin 15 disposed in the first cylindrical chamber 2 and extending towards the inner surface 16 of the first control spool 3 limits the piston motion and thus, initially, also the fuel quantity to be supplied to ignition fuel injectors 57, 58 by way of the first cylindrical chamber 2. Upon contact of the first control spool or piston 3 during the discharge motion with the contact pin 15, an electrical shifting signal is released in the manner which interrupts, for example, the positive circuit by means of a switch 59, thus causing a current coil 60 surrounding the right-hand portion of the cylindrical housing 1 to release the portion 61 of the second control spool 6 constructed as armature under the action of the compression spring 7. This releases the control pressure acting upon the first control spool or piston 3 by closing the bore 43 by means of the end section 44 of the second control spool or piston 6, thus enabling the first control spool or piston 3 to assume its initial position under the action of the return spring 4 so that the device can be charged again with the refilling valve 9 in the open position.

To enable the triggering of the electrical shifting signal, the actuating spool or shifting piston 12, its sleeve 13 as well as the cylinder 11 must be insulated against cylindrical housing 1 of the device.

As already mentioned, one end of actuating spool or shifting piston 12 is subjected to the action of return spring 17. The pressure of the discharge fuel prevailing in cylindrical chamber 2 acts upon the other end of the actuating spool 12; this means that the respective position of this actuating spool or shifting piston 12 is a function of that pressure differential which results from the spring tension, on the one hand, and the pressure of the of the discharge fuel, on the other. If, for example, the pressure of the discharge fuel decreases by a certain amount when the aircraft is operating at high altitude, this would result in a different position of the actuating spool or shifting piston 12. In this manner, the travel which the first control spool 3 has to traverse for discharging the fuel, and thus the discharge time as well as the ignition fuel quantity, which is to be supplied to the fuel ignition injectors 57, 58 can be controlled as a function of the given altitude.

This end of the actuating spool 12 can as well be subjected to the intake pressure of the compressor 19 of the engine 18 (FIG. 1) instead of being subjected to the action of return spring 17. For this purpose, a line 62 can be provided which is connected to cylinder 11 so that the air pressure tapped-off at the compressor intake, in lieu of the force of the spring 17, acts upon the actuating spool 12 by way of a bore in the cylinder 11.

The embodiment of the invention as shown in FIG. 2 essentially differs from that shown in FIG. 1 in that the cylinder 64 which includes a first control spool or piston 65 axially movable against the action of a return spring 66, is provided with bores 67, 68, 69. Lines 70, 71, 72 are connected to these bores 67, 68, 69 whereby pressure relief valves 73, 74, 75 are arranged in these lines. Lines 70, 71, 72 combine to form a common line 76 leading to the fuel tank 28 shown in FIG. 1.

The embodiment of FIG. 2 differes additionally from that of FIG. 1 in that the electromagnetic actuating device shown in FIG. 1 is replaced by a diaphragm 76' actuating the second control spool or piston 79, this diaphragm being subjected to a hydraulic control pressure acting in the direction of the arrow 77. On the left-hand side in the drawing, this diaphragm 76 includes a plunger 78 which engages in the second control spool or piston 79. This second control spool or piston 79 arranged in the associated cylindrical chamber 80 is movfrom which a line 86may lead to the fuel injectors 57, 58 of the engine (FIG. 1). The device is connected with the H.P. fuel system by way of the pump 31 and the line 87 shown in FIG. 1; the connection of the device with the L.P. fuel system is effected by way of the line 88 branched off at the fuel pump 32 (to FIG. 1), this line 88 again branching off into two lines 89, 90. During the charging motion of first control spool or piston 65, the line 89 is connected for that purpose with the cylindrical chamber 83 by way of the refilling valve 92; the second line branched off from the line 88 leads to bore 93 in the cylinder 64, by means of which the cylindrical chamber 80 can be charged with L.P. fuel with the second control spool or piston 79 in the end position as shown.

The device described above operates as follows:

If the engine afterburner (FIG. 1) is to be ignited, then the diaphragm 76 will be subjected to a pressure acting in the direction of arrow 77, thereby moving the second control spool or piston 79 towards the left against the spring 81. This opens the bore 94 supplied with H.P. fuel by way of the line 87, and the bore 93 for the LP. fuel supply is closed off. The H.P. fuel can now flow into the cylindrical chamber 80 by way of this bore 94 and another bore 95 extending through the second control spool 79. The fuel can then act upon the surface of the first control spool 65 which is opposite the spring 66 by way of the central bore 82 of the device, causing the spool 65 to move against the action of the return spring 66,,thus allowing ignition fuel to flow to the ignition injectors 57, 58 by way of the bore 84 and the line 86. During the described motion of the second control spool 79 to the left as a function of the pressure acting upon the diaphragm 76, the LP. fuel supply to cylindrical chamber 80 is thereby shut-off by the second control spool 79 sealing the bore 93.

It is essential therefore that the illustrated valves 73, 74, 75 are adjusted and designed in such a manner that they respond to different H.P. fuel pressures, i.e., during the discharge motion of the first control spool 65.

As a linear function of the increasing or decreasing pressure of the H.P. fuel due to higher or lower flight altitudes, these valves 73, 74, 75 can ensure a rapid ignition of the afterburner of as uniform a duration as possible. In addition to the ignition time, these valves 73, 74, 75, with a suitable arrangement and design thereof, can also control the amount of ignition fuel to be supplied as a function of time.

The embodiment as shown in FIG. 3 essentially differs from that shown in FIG. 1 in that a dropping resistor generally designated by reference numeral is provided, which is controlled by the given altitude, and which consists of a control spool or piston 104 arranged in a cylindrical chamber 102 and axially movable against the action of a return spring 103, whereby the spool or piston 104 is subjected to the compressor intake pressure of the engine 18 (FIG. 1) acting in the direction of arrow 101. The piston rod 105, designed as sliding contact 105' on its left-hand side, protrudes into a guide cylinder 106 mounted on the cylindrical housing 102. With the motion of the control spool 104, the sliding contact 105 can travel over an electrical resistor 107 connected to the positive circuit.

If, for example, the compressor intake or delivery pressure (arrow 101) of the compressor 19 associated with the engine 18 (FIG. 1) exceeds a predetermined given value, i.e., when an aircraft equipped with a device according to the invention descends from a relatively high altitude to a considerably lower flight altitude, this increase in the compressor intake pressure results in a motion of the control spool or,piston 104 and of the sliding contact 105 to the left and in a simultaneous increase in the resistance of line 108, which line is connected, on the one hand, with the sliding contact 105' and, on the other, with a current coil 110 surrounding a cylindrical guide means 111 of the device according to FIG. 3. This current coil 110 is connected with the negative circuit by way of the line 109.

During the discharge motion of the device, the lefthand section of the piston rod 114 associated with the control spool 112, which is constructed as magnet armature, is pushed into the area of the current coil 1 10, which is subjected to the voltage of the altitudecontrolled dropping resistor 100 by the resultant motion of the first control spool 112 against the action of the return spring 113. The inductive voltage which can be tapped-off at the current coil 110 is fed to an electric control device 116 of conventional construction by way of lines 114', 115. Upon deviation from a specified nominal voltage of the current coil 1 l0, and with simultaneous action of the altitude-controlled dropping resistor 100, this control interrupts the power supply by way of lines 1 l7, 1 18 to the current coil 60, thus causing, as already described in connection with FIG. 1, the second control spool or piston 6 in the shown end position under the influence of the compression spring 7 to close the bore 43 by means of the end section 44 and thus cutting off the H.P. fuel supply.

The recharging motion of the control piston 112 toward the right takes place due to the release action of the return spring 113 by the control pressure of the H.P. fuel derived from the side of the control piston opposite the return spring 113 during which motion the refilling valve 9 is opened due to the pressure drop in the cylindrical chamber 2 and allows the LP. fuel supplied by pump 32 (FIG. 1) to flow through the lines 46, 47. For reasons of simplicity, the refilling valve 9 which corresponds to that of FIG. 1 is only schematically illustrated and indicated in FIG. 3 only by a reference numeral.

With the arrangement of the device for metering the ignition fuel as shown in FIG. 3, including the altitudecontrolled dropping resistor 100 as well as the piston rod 114 designed as magnet armature associated with the control spool 112, and the current coil 110, it is therefore possible, under conditions of high-flight altitude, at low compressor intake pressure (arrow 101) and at low H.P. fuel pressure, to achieve a discharge time of the ignition fuel to ignition injectors 57, 58 (FIG. 1) which does not exceed that time period required for operation at low altitude, so that the turbine 23 associated with engine 18 (FIG. 1) is not endangered.

In the case of the device according to FIG. 3, the maximum control stroke of the first control spool 112 will be limited for this purpose, i.e., the discharge motion thereof will be interrupted immediately upon reaching a specified voltage, stored in the electric control 116, which shuts off the power supply to current coil 60 thus causing the second control spool or piston under the influence of the compression spring 7 to close the bore 43 for the H.P. fuel to be supplied.

While I have shown and described several embodiments in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What I claim is:

1. A device for metering ignition fuel to an ignition means of an afterburner associated with a turbojet engine, the turbojet engine having parameters which vary with changing ambient conditions and the metering including metering parameters of injection time and injection fuel quantity, the device having a first cylinder means forming a first chamber for charging and discharging as well as for storing the ignition fuel, said first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of'the afterburner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber, and a second cylinder means forming a second chamber arranged adjacent to the other end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action of a second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous closing of a low-pressure fuel supply for the discharging motionof the first control means or for closing the high-pressure fuel supply with simultaneous opening of the low pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient conditions, the control means including a third control cylinder arranged adjacent the one end of the first cylinder means and having an axially movable actuating third piston therein, the third piston having a first portion acted upon by an elastic force in the third control cylinder and having a second portion including a contact pin extending into the first chamber acted upon by the pressure of the discharge fuel, the contact pin being arranged to contact a surface of the first control piston means during the discharging motion thereof for initiating an electrical shut-off signal for the solenoid valve.

2. A device according to claim 1 characterized in that the elastic force acting upon the first portion of the actuating third piston is produced by a spring disposed in said third cylinder for biasing the actuating piston.

3. A device according to claim 1, characterized in that the elastic force acting upon the first portion of the actuating third piston is produced by a pressure medium which varies as a function of the varying parameters of the engine and which is supplied to the third cylinder.

' charging as well as for storing the ignition fuel, the first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of the after burner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber and a second cylinder means forming a second chamber arranged adjacent to the other end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action ofa second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous opening of the low-pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient conditions, the control means includes a cylindrical guide means adjacent the one end of the first cylinder means, a current coil surrounding the guide means and avariable resistor responsive to altitude connected to the current coil, the first control piston means being provided with a piston rod arranged for movement into the area of the cylindrical guide means during the discharging motion thereof for inducing a voltage in the current coil in accordance with the displacement of the piston into the area of the cylindrical guide means, and means for tapping off the voltage induced in the current coil and for controlling the solenoid valve in accordance therewith.

6. A device according to claim 5, characterized in that the control means control both the injection time and ignition fuel quantity as a function of the engine parameters.

7. A device for metering ignition fuel to an ignition means of an afterburner associated with a turbojet engine, the turbojet engine having parameters which vary with changing ambient conditions and the metering including metering parameters of injection time and injection fuel quantity, the device having a first cylinder means forming a first chamber for charging and discharging as well as for storing the ignition fuel, the first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of the afterburner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber, and a second cylinder means forming a second chamber arranged adjacent to the one end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action ofa second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous closing of the low-pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient condition, the control means including means responsive to the discharging motion of the first control piston means for providing a shut off signal for the solenoid valve as a function of the varying parameters of the engine.

8. A device according to claim 7, characterized in that the control means includes a third cylinder means adjacent the first cylinder means and third piston means arranged for axial movement therein the third piston means having a portion thereof arranged within the first chamber and being responsive to the discharging motion of the first control piston means for moving within the third cylinder means, the control means providing a shut off signal for the solenoid valve in response to the movement of the third piston means.

9. A device for according to claim 8, characterized in that an elastic force means is arranged in the third cylinder for biasing the third piston means;

10. A device according to claim 9, characterized in that the elastic force means is a spring.

11. A device according to claim 9, characterized in that the elastic force means is a pressure medium which varies as a function of the varying parameters of the en- I gine which is supplied to the third cylinder.

12. A device according to claim 11, characterized in that the pressure medium varies in accordance with flight altitude of the engine.

13. A device according to claim 7, characterized in that the control means control both the injection time and injection fuel quantity as a function of the engine parameters.

t k a: a 

1. A device for metering ignition fuel to an ignition means of an afterburner associated with a turbojet engine, the turbojet engine having parameters which vary with changing ambient conditions and the metering including metering parameters of injection time and injection fuel quantity, the device having a first cylinder means forming a first chamber for charging and discharging as well as for storing the ignition fuel, said first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of the afterburner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber, and a second cylinder means forming a second chamber arranged adjacent to the other end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action of a second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous closing of a low-pressure fuel supply for the discharging motion of the first control means or for closing the high-pressure fuel supply with simultaneous opening of the low pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient conditioNs, the control means including a third control cylinder arranged adjacent the one end of the first cylinder means and having an axially movable actuating third piston therein, the third piston having a first portion acted upon by an elastic force in the third control cylinder and having a second portion including a contact pin extending into the first chamber acted upon by the pressure of the discharge fuel, the contact pin being arranged to contact a surface of the first control piston means during the discharging motion thereof for initiating an electrical shut-off signal for the solenoid valve.
 2. A device according to claim 1 characterized in that the elastic force acting upon the first portion of the actuating third piston is produced by a spring disposed in said third cylinder for biasing the actuating piston.
 3. A device according to claim 1, characterized in that the elastic force acting upon the first portion of the actuating third piston is produced by a pressure medium which varies as a function of the varying parameters of the engine and which is supplied to the third cylinder.
 4. A device according to claim 1, characterized in that said control means control both the injection time and ignition fuel quantity as a function of said engine parameters.
 5. A device for metering ignition fuel to an ignition means of an afterburner associated with a turbojet engine, the turbojet engine having parameters which vary with changing ambient conditions and the metering including metering parameters of injection time and injection fuel quantity, the device having a first cylinder means forming a first chamber for charging and discharging as well as for storing the ignition fuel, the first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of the after burner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber and a second cylinder means forming a second chamber arranged adjacent to the other end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action of a second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous opening of the low-pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient conditions, the control means includes a cylindrical guide means adjacent the one end of the first cylinder means, a current coil surrounding the guide means and a variable resistor responsive to altitude connected to the current coil, the first control piston means being provided with a piston rod arranged for movement into the area of the cylindrical guide means during the discharging motion thereof for inducing a voltage in the current coil in accordance with the displacement of the piston into the area of the cylindrical guide means, and means for tapping off the voltage induced in the current coil and for controlling the solenoid valve in accordance therewith.
 6. A device according to claim 5, characterized in that the control means control both the injection time and ignition fuel quantity as a function of the engine parameters.
 7. A device for metering ignition fuel to an ignition means of an afterburner associated with a turbojet engine, the turbojet engine having parameters which vary with changing ambient conditions and the metering including metering parameters of injection time and injection fuel quantity, the device having a first cylinder means forming a first chamber for charging and discharging as well as for storing the ignition fuel, the first cylinder means having charging fuel inlet means and discharging fuel outlet means at one end thereof, a first control piston means being axially movable in said first cylinder means and having a discharging motion in a first direction against the action of a first return spring for discharging the fuel in the first chamber to the ignition means of the afterburner of the engine and having a charging motion in a second direction for the charging of fuel in the first chamber, and a second cylinder means forming a second chamber arranged adjacent to the one end of the first cylinder means and being in fluid communication with the first chamber, a second control piston means in said second cylinder means actuated by an external source and axially movable against the action of a second return spring, the second control piston means including means for either opening a high-pressure fuel supply with simultaneous closing of the low-pressure fuel supply for the charging motion of the first control piston means, characterized in that the second control piston means is a solenoid valve and the external source provides an electrical signal for actuating the solenoid valve, and in that control means are provided for controlling at least one of the two metering parameters consisting of injection time and ignition fuel quantity as a function of the parameters of the turbojet engine varying with changing ambient condition, the control means including means responsive to the discharging motion of the first control piston means for providing a shut off signal for the solenoid valve as a function of the varying parameters of the engine.
 8. A device according to claim 7, characterized in that the control means includes a third cylinder means adjacent the first cylinder means and third piston means arranged for axial movement therein the third piston means having a portion thereof arranged within the first chamber and being responsive to the discharging motion of the first control piston means for moving within the third cylinder means, the control means providing a shut off signal for the solenoid valve in response to the movement of the third piston means.
 9. A device for according to claim 8, characterized in that an elastic force means is arranged in the third cylinder for biasing the third piston means.
 10. A device according to claim 9, characterized in that the elastic force means is a spring.
 11. A device according to claim 9, characterized in that the elastic force means is a pressure medium which varies as a function of the varying parameters of the engine which is supplied to the third cylinder.
 12. A device according to claim 11, characterized in that the pressure medium varies in accordance with flight altitude of the engine.
 13. A device according to claim 7, characterized in that the control means control both the injection time and injection fuel quantity as a function of the engine parameters. 